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src/judy-1.0.5/test/timeit.c  view on Meta::CPAN

	ztime = 0.0;

	for (i = 0; i < 100; ++i)	// average many runs.
	{
	    STARTTm(tm2);
	    ENDTm(DeltaUSec, tm2);
	    ztime += DeltaUSec;
	}
	ztime = ztime / ((double) i);


// SIMPLE TESTS OF TIMER OVERHEAD:
//
// Make two passes at both the high-res (if any) and slower timers.

	(void) puts("\nTiming timers themselves: start, end, end");

#define	PRINTPASS(Desc,Pass)						\
	(void) printf("%-8s pass %d:  %f - %f = %f usec\n", Desc, Pass,	\
		      usec[((Pass) * 2) - 1],  usec[((Pass) * 2) - 2],	\
		      usec[((Pass) * 2) - 1] - usec[((Pass) * 2) - 2])

#ifdef _TIMEIT_HIGHRES
	START_HRTm(tm2);
	END_HRTm(usec[0], tm2);	// throw away in case of sleep(1) here.

	START_HRTm(tm2);
	END_HRTm(usec[0], tm2);
	END_HRTm(usec[1], tm2);

	START_HRTm(tm2);
	END_HRTm(usec[2], tm2);
	END_HRTm(usec[3], tm2);

	PRINTPASS("High-res", 1);
	PRINTPASS("High-res", 2);
#endif

	STARTTm(tm2);
	ENDTm(usec[0], tm2);	// throw away in case of sleep(1) here.

	STARTTm(tm2);
	ENDTm(usec[0], tm2);
	ENDTm(usec[1], tm2);

	STARTTm(tm2);
	ENDTm(usec[2], tm2);
	ENDTm(usec[3], tm2);

	PRINTPASS("Non-HR", 1);
	PRINTPASS("Non-HR", 2);


// PRINT INITIAL INFO:

#ifdef _TIMEIT_HIGHRES

// Print the CPU speed:
//
// Note:  USecPerClock is a global set by the first instance of STARTTm.  You
// can also get this number by calling find_CPU_speed().

	(void) printf("\nClock step = %.3f nsec => %.1f MHz.\n",
		      USecPerClock * 1000.0, 1.0 / USecPerClock);
#endif

// Print timer overhead even though it's been subtracted from the reported
// results.

	(void) printf("Timer overhead subtracted from the times below = %f "
		      "usec.\n", ztime);


// DO A FAST TIMER CHECK:

	(void) puts("\nCheck timer precision by repeating the same action:");
	(void) puts("Times in each group should be close together.");
	(void) puts("\nTiming something very fast: \"++i\":");

	mintime = MAXDOUBLE;

	for (i = 1; i <= i_max; ++i)
	{
	    prevtime = DeltaUSec;
	    STARTTm(tm2);		// start the timer.
	    ++i;			// statement to time.
	    ENDTm(DeltaUSec, tm2);	// stop the timer.
	    DeltaUSec -= ztime;		// remove timer overhead.

// Throw away the first loop iteration to warm up the cache:

	    if (--i > preload)
	    {
		if (mintime == MAXDOUBLE) mintime = DeltaUSec;

		(void) printf("%3d. %8.3f nanosec,\tmintime diff %8.1f %%\n",
			      i - preload, DeltaUSec * 1000.0,
			      ((DeltaUSec - mintime) * 100) / mintime);

		if (DeltaUSec < mintime) mintime = DeltaUSec;
	    }
	}


// TIME A FUNCTION CALL:

	(void) puts("\nTiming a function: \"gettimeofday()\":");
	mintime = MAXDOUBLE;

	for (i = 1; i <= i_max; ++i)
	{
	    prevtime = DeltaUSec;
	    STARTTm(tm2);			// start the timer.
	    gettimeofday(&tmjunk, NULL);	// burn some cycles.
	    ENDTm(DeltaUSec, tm2);		// stop the timer.
	    DeltaUSec -= ztime;			// remove timer overhead.

// Throw away the first loop iteration to warm up the cache:

	    if (i > preload)